1. Field of the Invention
The present invention relates to safety cabinets for storage of combustible, volatile or other hazardous materials and more specifically to safety cabinets having doors which are self-closing in a sequential order and are self-latching at three points following closing.
2. Description of Prior Art
Use of safety cabinets for storage of paints, solvents, lubricants and various other combustibles, volatile and hazardous materials is required by most safety regulations and fire codes. To isolate the interior of the cabinet and protect its contents from the heat and flames of a fire or to contain a fire within the cabinet, door(s) of a safety cabinet, in most cases, have a fusible link to trigger self-closing of the door(s) when the fusible link reaches a selected temperature. Cabinets having two doors utilize sequencing mechanisms to assure that a particular door closes prior to the other door so as to obtain a seal at a lip which extends from the edge of one of the doors and overlaps the other door.
To provide a more secure enclosure and maximize safety, a self-latching mechanism is utilized to latch the doors following self-closing. Most safety regulations require latching at three points on the cabinet. Examples of such self-latching mechanisms are described in U.S. Pat. Nos. 4,146,944 and 4,265,051, both with Williams as the inventor, which describe a "three-point latching mechanism" which includes a center latch and a pair of vertically oriented rods, a top rod extending from the latch mechanism to the top edge of the door and a bottom rod extending from the latch mechanism to the bottom edge of the door. When in latched position the center latch engages a second door and ends of the rods extend through apertures in the door frame. The mechanism is biased by a spring toward the latched position but is restrained from reaching that position by a notch in the bottom rod which fits over a bracket positioned on the door near the lower end of the bottom rod. The notch is biased to catch on the bracket by a leaf spring acting on the rod. When the door is closed the bottom rod contacts an upturned flange on the door housing to release the notch from the bracket and allow the latch and rods to engage.
U.S. Pat. No. 5,061,022 describes a latching mechanism which includes a latch spring biased to move to a latched position and a plurality of levers. The latch is prevented from latching by a locking pin engaged in a positioning lever slot. The pin is disengaged from the slot when an actuating lever contacts a jamb stop when the door is closed. The jamb stop is located in the side door jamb to which the door is hinged.
U.S. Pat. No. 4,262,448 describes a latching mechanism having a center latch and a top and a bottom latch rod which engages the top and bottom frame of the cabinet. The mechanism is spring biased toward a latched position. The top rod incorporates a shoulder which engages a latch bracket and a leaf spring biases the rod to maintain the engagement. Upon closing the door a latch stop in the top frame of the cabinet contacts the rod to dislodge the shoulder from the latch bracket which allows the biased latching mechanism to latch.
U.S. Pat. No. 4,619,076 describes a latching mechanism having a latch rod with an inclined upper end. The rod is spring biased toward an upward latched position. Upon closing of the door the inclined upper end of the rod contacts a top frame of the cabinet which forces the rod downward to pass by a corner of the frame and then engage an aperture in the frame when the door is completely closed.